Defense lawyers at Bill Cosby's retrial on sexual assault charges can call a witness they say will undermine his accuser's credibility, a Pennsylvania judge said on Tuesday, reversing his ruling on that witness in the first trial that ended with a hung jury.

The ruling to allow Margo Jackson's testimony came from Montgomery County Judge Steven O'Neill as the second day of jury selection got underway in Norristown, Pennsylvania. It was a victory for Cosby's legal team, which had argued that her testimony will be central to their argument that Andrea Constand's claim of assault is untrue.

Cosby, 80, is facing his second criminal trial on charges that he drugged and sexually assaulted Constand at his home in suburban Philadelphia more than 14 years ago. The first trial end in a mistrial last June when the jury could not come to a verdict.

The entertainer, best known for his role as the wise and witty dad on the television series "The Cosby Show," has denied allegations from more than 50 women that he sexually assaulted them. Constand's accusations are the only ones recent enough to allow for criminal prosecution.

Defense lawyers had asked O'Neill to permit Jackson, a former acquaintance of Constand's, to testify that Constand once told her she could make money by accusing a famous person of sexual assault.

During the first trial, O'Neill barred Jackson from taking the stand as a rebuttal witness, ruling that the statements were hearsay. But he changed his mind following both written submissions and oral arguments at pretrial hearings last week.